A 14-year-old female patient with a history of ocular allergy controlled with eye drops and progressive advanced keratoconus (KC) in both eyes presented for evaluation, complaining of worsening of the vision in both eyes in the last 6 months. Despite having new rigid contact lenses (RCLs), she was unable to wear them long enough to perform her daily activities. On her examination, best spectacle-corrected visual acuity (BSCVA) was 20/100 in both eyes. The slit-lamp examination demonstrated corneal ectasia with mild Vogt’s striae and central corneal thinning with mild paracentral anterior corneal opacity in both eyes. Tomographic evaluation confirmed advanced KC with a simulated steep K of 64.3 diopter (D) in the right eye ( Fig. 40.1 ) and 64.2 D in the left eye ( Fig. 40.2 ), with the thinnest point of 329 μm in the right eye (see Fig. 40.1 ) and 385 μm in the left eye (see Fig. 40.2 ).
As the patient had low BSCVA and was unable to adapt to RCLs in both eyes, intrastromal corneal ring segments (ICRS) were indicated. Because the patient was at a higher risk age for progression of ectasia and already had high keratometric values, combined corneal cross-linking (CXL) was recommended to decrease the risk of progression. As the pachymetry without epithelium would be less than 400 μm in both eyes, accelerated CXL using 9 mW/cm 2 for 10 minutes with hypo-osmolar riboflavin was performed. Because the tomographic examinations showed high keratometric values, long-arc ICRS were implanted ( Figs. 40.3 and 40.4 ) in both eyes to achieve the greatest possible applanation effect.
Three months after the procedure her BSCVA improved to 20/40 in the right eye and 20/30 in the left eye, with the tomographic examinations showing 10.7 D of applanation in the simulated steep K of the right eye ( Fig. 40.5 ) and 11.6 D of applanation in the left eye ( Fig. 40.6 ), remaining stable during follow-up.
A 25-year-old female patient with history of ocular allergy controlled with eye drops and advanced KC with well-adapted RCLs in both eyes presented for evaluation complaining of worsening vision and frequent need to change the RCL of the left eye in the last year. She said that in the follow-up carried out in her city of origin, the examinations had shown stability of the KC in the right eye and progression in the left eye, but that they did not indicate CXL in the left eye, because of a very thin cornea. On her examination, best contact lens–corrected visual acuity (BCLVA) was 20/30 in both eyes. The slit-lamp examination demonstrated corneal ectasia with Vogt’s striae and central corneal thinning with mild central anterior corneal opacity in both eyes. The tomographic evaluation confirmed advanced KC with a simulated K of 62.9 D in the left eye, with the thinnest point of 279 μm ( Fig. 40.7 ) and around 220 μm without epithelium, measured by optical coherence tomography (OCT) ( Fig. 40.8 ).
Although the patient had good BCLVA and was well adapted to contact lenses, the left eye was progressing but did not have sufficient corneal thickness to perform CXL; thus Bowman’s layer transplantation (BLT) assisted by femtosecond laser (FSL) was indicated in the left eye.
Three months after the procedure her BCLVA was maintained at 20/30 in the left eye, with the well-positioned BLT graft visible on the OCT ( Fig. 40.9 ) and the tomographic examinations showing 2.9 D of applanation in the simulated K ( Fig. 40.10 ), remaining stable during follow-up.